Crown block



Dec. 2, 1930 w. D. DAVIDSON CROWN BLOCK Filed Jan. 9, 1928 2Sheets-Sheet 2 EA/T012. WILL/HM D. DH IDSON, B)

HT TozaA/BK block,

Patented Dec. 2, 1930 BUNITEDISTATES PATENT OFFICE WILLIAM nInnvrnsolv,or Los A enLrls, onnrronnranssreivon 'IO EMSCO DERRICK & EQUIPMENTooMrANY. 013 LOS ANGELES, CALIFORNIA, VA CORPORATION or GALI- roamsoaowiv BLOCK Application filed, January 9, 1928. Serial'No/2 i5,5 90.

erected with the vertical axis thereof coinciding with the verticalaxisof the proposed well, In carrying out the drilling operation,

heavy tools and sections of tubing must be,

suspended within the derrick substantially on the vertical axisthereofso that these may be hoisted or lowered at will. To effect this, tackleis rigged up which includes a multiple sheave traveling block and amultiple sheave crown block, the latter being stationary and mountedupon the top of the derrick. A.

cable, which is wound around the sheaves of the blocks to complete thistackle, is connected to the drum of a draw Works whichis power operatedso as to raiseor lower the traveling In the older s of crown blocks ingeneral use, light hoisting within thederrick was accomplished by acable wound around a sand reel and passed over a sheave mountedon thesame shaft with the sheaves of the crown block utilized for the tacklecable. This caused the lighthoisting cable to lift on a line disposed aconsiderable" distance from the central axis of the derrick which causedbinding of the joints of'the element lifted upon when it was desired toseparate these at the floor of the derrick. A novel crown block in whichthis difiiculty was eliminated is shown in the patent to Edwin 0..Bennett, No. 1,673,346, for crownblock, dated June. 12,

1928' In'the Bennett crown block, theglight i lifting sheaves aredisposed'betweena pair of l-beains which rest upon the water'table ofthe derrick. The stationary block sheaves of the derrick tackle arerotatable on an axle disposed perpendicular to the axes of the lighthoisting sheaves, and-which is mounted upon a pair of I-beams which aredisposed in perpendicular relation with and rest upon the I-beaniscarrying the light hoisting sheaves. In the Bennett crown block, thestationary .tackle sheaves are termed the'upper sheaves and the lighthoisting sheaves disposed therebelow are termed the lower sheaves. The otruct n o h Bennet s e s b o stock.

thirty inches in d1a1neter,'itwas necessary makes it possible for theupper sheaves to be disposed close together so that the various turns ofcable in the tackle are substantially parallel, which permits thetraveling block to be drawn upward until it. contacts the crown blockwithoutfthe cable binding on the sheaves of either block. In usingtheBennett crown block, therefore, drillers have found it diflicult toavoid the lower sheavesbeing darnaged by .the traveling block strikingthese,

and frequently fragments have been broken from the lower blocks which,falling downward through thederrick, have menaced the lives of thedrilling crewworking on the floor, of the derrick. i

It is correspondingly an object of my invention to provide a crown blockconstruction in which 'a pair of lower sheaves is protected from beingdamaged when the traveling block of the derrick tackle is liftedv intocontact with the crown block.

Heretofore, the I-bearns, bywhich the lower sheaves of the Bennett crownblockwere supported, have been inside from standard rolled Owing tothe", lower sheaves being that the I-beams on which the supportedsheaves were mounted be twenty inches in height. In order to secure thedesired compactness of the crown block with the lower beams of thisheight, the lower portion of theends of these I-beains were notched soas to receive-opposite wooden members of the water table of the derrick,and the shafts on which the lower sheaves rotatedwere mounted along thelower edges of these notched ,I-' 'bealns. This construction does, notprovide adequate support for the lower sheaves, and a more rigid supportfor the lower sheaves has been found necessary;

It istherefore a further object. of my invention to provide a crownblock of the Bennett type in which the supports for the lower sheavesthereof are of ample strength to rigidly support these sheaves'and, atthe same time, owing to the form of their construction, to protect thelowersheaves against damage by the traveling block on its upward movInent.

n ther o je of my i ntio s to Pr Ill vide a crown block assembly havingsheaves over which a cable extends, which cable also extends around atraveling block, lower sheaves disposed below the upper sheaves, andmeans for protecting the lower sheaves so that the traveling blockcannot engage them.

Further objects and advantages will be made manifest in the followingdescription and accompanying drawings in which a preferred embodiment ofmy invention is illustrated. Referring to the drawings, which are forillustrative purposes only:

Fig. 1 is a diagran'nnatical view illustrating a derrick on which thecrown block of my invention is adapted to be used.

Fig. 2 is a fragmentary sectional view showing the manner of rigging thederrick tackle upon the crown block.

Fig. 3 is'a vertical sectional view through the crown block of myinvention, partly in elevation, the sectioned portions of F ig. 3 beingtaken on planes indicated by the line 33 of Fig. 4.

Fig. 4 is a verti a1 sectional view taken as indicated by the line 44 ofFig. 3.

Referring specifically to the drawings:

Fig. 1 shows a typical well drilling derrick 10, which includes fourinwardly sloping legs 11 which are interconnected and braced by girts 12and struts 13. Mounted on top of the legs 11 is a water table 15 whichis a four sided wooden structure having an inner opening about live feetsquare. Mounted upon the water table 15 is the crown block 16 of myinvention.

As clearly shown in Figs. 3 and 4, the crown block 16 includes a lowerframe work 18 and an upper frame work 19 which are disposed in crossedrelation. The lower frame work 18 includes a pair of outer I- beams 20which is secured as by bolts 21 to the water table 15. Disposedcentrally within the water table 15, and mounted on opposite sidesthereof so as to be parallel with each other and the side beams 20, arelower sheave beams 24. Each of the beams 24 includes a web 25, the outerend portions 26 of which are substantially 12 inches deep and rest uponthe water table 15, while the central portions of the webs aresubstantially 33 inches in depth and extend downward over 21 inches intothe square central space of the water table 15. Opposite sides of theupper and lower edges of each of the webs 25 are reinforced by angleirons 28 and 29, which conform to these edges and are riveted to thewebs 25. Disposed between the beams 24, on opposite sides of the centralaxis of the derrick 10, are lower sheaves 30 which are pivotally mountedupon shafts 31 and 32, and which are supported in split bearing blocks33 and 34 which are secured as by bolts 35 to opposite sides of the webs25 of the beams 24, so that the bearings 33 and 34 are in horiupperzontal alignment with each other. The

sheaves 30 are preferably 30 inches in diameter, but it is to beunderstood that these dimensions are for the purpose of indicatingproportion and are not essential to the invention.

The shaft 32 extends outward beyond the bearing 34, in which it issupported, and receives a small sheave 36, the purpose of which will bedescribed later. v

It is to be noted that in the construction of the lower frame 18 of thecrown block 16, the beams 24 extend downward some distance below thelower portions of the sheaves 30, and that the bearing blocks 33 and 34upon which these sheaves are supported are secured to the webs 25 of thebeams 24 at points substantially intermediate the upper and lower edgesof these beams. Thus, not only is protection afforded to the sheaves 30,but the beams 24 are made much stronger than those previously usedwithout increasing the height to which the crown block 16 extends abovethe water table 15 upon which it is mounted.

The upper frame 19 includes a pair of I-beams 40, held in spacedrelation by spanners 41 and rigidly secured by bolts 42 to the I-beams20 of the lower frame 18. Disposed between the beams is a series ofstationary tackle-block sheaves 43 which rotate and are supported upon ashaft 44 resting on the I-beams 40 and secured thereto by clamps 45.

The derrick 10 has a floor upon which are rotatably mounted a bull wheel51, a calf wheel 52, a sand reel 54, and a draw works having a cabledrum 56. In using the lower sheaves 30 for light hoisting, a cable 58may be unreeled from the sand reel 54 and run over one of the sheaves 30so that it extends downward substantially 0n the axis of the derrick 10.The other sheave 30 is utilized by unwinding a cable 59 from the bullwheel 51, passing it over the other sheave 30 and extending it downwardadjacent to the axis of the derrick.

In assembling the derrick tackle, a. traveling block 60 is providedwhich has a plurality of sheaves, one less in number than that of thesheaves 43 of the crown block 16. The cable 62 is extended from the drum56 of the draw works 55 and wound consecutively about respective pairsof the sheaves 43 and the sheaves of the traveling block 60, so that thecable 62, after passing over the last of the sheaves 43, passes downwardso that its direction is changed by the small sheave 36. and from thissheave extends to the calf wheel 52. The draw works drum 56 rotates onan axis parallel with the axis of the sheaves 43 so that the cable 62,passing between the draw works drum and one of the sheaves 43, liessubstantially in the plane in which this sheave rotates so as not towear the side flanges of this sheave. The calf wheel 52, on

the other hand, rotates on an axis perpendicular relative to the axis ofthe sheaves 43 so that the small sheave 36 is required to give thechange'of direction to the cable 62 after it leaves the rest of thesheaves 43 over which it is wound and extends to the calf wheel 52.

As will be seen by observation of Fig. 2,

when the derrick tackle is operated by winding in the cable 62 heldupon, the draw works drum 56 on the calf wheel 52- so as to raise thetraveling block 60 into contact with the crown block 16, the travelingblock 60 abuts against the lower edges of the beams 24 so that thesheaves 30 are entirely protected from damage by accidental contact withthe traveling block 60. The angles 29 form wide abutting edges for thetraveling block to engage.

It will be seen that my invention in its broadest conception consists orthe particular shape of the lower sheave supporting means in order toprotect them, and it further consists in the idea of providing a guardmeans at the lower part of the lower sheaves so that a traveling blockcannot engage the lower sheave or sheaves. The guard means of theinvention is shown as being integral with the lower sheave supportmeans, but it is of course obvious that these parts could be madeseparate if desired.

I claim as my invention:

In a crown block construction the combination of: a frame including apair of members, end portions of which are adapted to rest upon thewater table of a derrick, and a central portion of which extendsdownwardly from said end portions; and a pair of lower sheaves rotatablymounted between said central portions of said frame members, the

' lower edges of said central portions being disposed below the lowerportions of said 7 sheaves.

In testimony whereof, I have hereunto set my hand at Los Angeles,California, this 31 day of Dec., 1927.

WILLIAM D. DAVIDSON.

